Hi,

We are trying to obtain a callgraph using 'perf' utility, while running on MIPS 
architecture with linux 3.10 (64Bit processes)
We wish to obtain callgraph on:

·         Terminated processes

·         Running processes (using -p <pid>)

Following the resolution that perf is unable to create callgraph on MIPS using 
frame pointer, we tried using libunwind
Since 'dwarf' option for perf isn't part of linux 3.10 (or any other version), 
we added a patch (composed of the following 3 patches):

·         https://www.linux-mips.org/archives/linux-mips/2013-05/msg00123.html

·         https://www.linux-mips.org/archives/linux-mips/2013-05/msg00115.html

·         https://www.linux-mips.org/archives/linux-mips/2016-04/msg00003.html

·         As part of the patch we also linked 'perf' with 'libunwind' (open 
source version 1.2.1).

This patch added the 'dwarf' capability to 'perf' on MIPS, however we still 
couldn't obtain a usable callgraph (most functions had no trace)
The problem we encountered was that when reaching 'maps__find´ function 
(linux/tools/perf/util/map.c), the binary search for the required entry failed 
(could not be located)
>From our investigation, we can support local unwinding but not remote (which 
>is the type of unwinding required by 'perf')

Checking online we saw on 'libunwind' NEWS: '** Mips remote unwind support' for 
version 1.3.
We replaced our '1.2.1' version with '1.3-rc1' and re-checked, however the 
results remained the same (no callgraph).

Could you please assist?

·         What was the issue you encountered that the fix in 1.3 version 
resolved?

·         Can the new addition enable 'perf' to support callgraph on MIPS?

·         Did we miss anything in our steps (as described above)?

·         Can you advice on the next steps?

Thanks,
Sapir

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